The present invention relates to a wire transfer assembly which provides for the continuous and uninterrupted removal of wire from adjacently positioned wire spools or reels.
In applications such as, but not limited to robotic welding, welding wire is supplied to the welding station by continuously withdrawing and removing the welding wire from a wire coil or spool. Robotic welding stations utilize massive amounts of welding wire and the coils or spools may vary in size from 40 to 50 pounds up to and exceeding about 1,000 pounds. Accordingly, it is very desirable to have as a source of welding wire an assembly which permits the continuous and uninterrupted withdrawal of wire from a wire source which will eliminate the need for stopping the welding operation while the empty coil, reel or spool is removed and a subsequent coil of welding wire is positioned and coupled to supply the welding station. Such downtime is expensive and substantially reduces the efficiency of the welding operation, particularly when the welding station is associated with and part of a continuously running assembly line.
In order to overcome the problems of stopping and replacing the wire coil or spool in wire handling operations, it has been suggested that adjacent coils or spools of filament wire may be secured together by attaching the trailing wire end from one coil to the leading wire end of another coil. Thus, when the wire is fully removed from one spool, then the second spool provides an uninterrupted and continuous supply of wire. However, in applying such a system to robotic welding operations, it has not been possible to readily position a wire guide coaxially with respect to the coil axis of each of the supply coils of wire. One attempt at a solution to this problem has involved a complicated coil or spool support system which is employed to somehow tilt the spool and direct the imaginary coil axis of each of the spools of wire to a fixed eyelet. However, such assemblies are complex, expensive and unworkable in welding wire systems because of the size of the welding wire spools, space limitations and the requirement that the welding wire entering the wire guide not have distortion imparted therein where the wire is passed over the edges of the wire guide.
Accordingly, the alignment of the wire guide coaxially with the coil axis is very desirable and important in robotic welding because the removal of welding wire from the wire spool through the wire guide must be substantially free of back tension and must not impart a cast or otherwise alter the shape of the wire during removal of the welding wire from the spool. When a cast is imparted to the withdrawn welding wire, the resultant flip, arc outages, inconsistent feed and misalignment at the welding electrode of the welding machine result in inadequate and imprecise welding operations oftentimes resulting in discarding or reworking of expensive parts.
Additionally, such prior art payoff or wire removal assemblies generally include complicated take-off assemblies which include a flyer arm and an eyelet which revolves about the coil axis to remove the wire from the coil. Such rotatable arm assemblies complicate and increase the difficulties in maintaining alignment of the upper wire guide removal unit with respect to the coil axis, particularly when continuous wire withdrawal from adjacent spools is desired. Accordingly, such assemblies have not been acceptable in handling welding wire in robotic welding operations.